3 ACL Injury Approximately 80,000 tears/year in the US50,000 reconstructions/year ($1 billion)15-25 years old70 % sports relatedAbsolute numbers show males > femalesHowever, in sports where both men and women compete, women are 2-8 times more likely to tear their ACL

15 Anatomic Risk Factors Laxity Notch Size More common in women than menRole in injury still unclearNotch Size9 of 15 studies support narrow notch width as a contributing factorIn general, notch width is more narrow in women

16 Hormonal Risk FactorsEstrogen and Progesterone receptors found on the ACLThey can influence the mechanical properties of the ACLHigher estrogen levels reduces the tensile strength of rabbit ACL

17 Hormonal Risk FactorsStudies attempting to link ACL injury with menstrual cycle are conflictingSurvery of 103 ACL injuries in NCAA womens basketball players from showed injury most commonly occurred in the peri-menstrual peroid (just before or just after)Role of oral contraceptives is still unknown

18 Biomechanical Risk FactorsProprioception and neuromuscular controlHamstring and Quad balanceWomen tend to have less hamstring activation than menEccentric quad contractionHip extensor strengthWomen tend to have weaker hamstrings and glutei which leads to more upright landings after jumpsMore valgus knee angle in women increases stress on the ACL